Soil pH in Kodiak Island Borough, AK: Lime or Sulfur?

Typical topsoil pH in Kodiak Island Borough, AK

Typical topsoil in Kodiak Island Borough, AK is pH 4.96, too acidic for vegetable garden. Expect roughly 4.5 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Kodiak Island Borough needs, by plant

• Already in range: blueberries, azaleas and rhododendrons.
• Just outside, test first: potatoes (off by 0), blue hydrangeas (off by 0).
• Lime: lawn (cool-season grass) 4.5 lb/100 sq ft; vegetable garden 4.5 lb/100 sq ft; tomatoes 4.5 lb/100 sq ft; strawberries 3 lb/100 sq ft; roses 4.5 lb/100 sq ft; pink hydrangeas 3.9 lb/100 sq ft.

What to do next

If your test confirms pH near 4.96, spread about 45 lb of ground limestone per 1,000 sq ft of vegetable bed, ideally in fall.

How mixed the soil is

Of the 2,852,872 surveyed acres in Kodiak Island Borough, AK, 80% are strongly acidic (below 5.5), 20% are moderately acidic (5.5-6.5). Mapped soils run from pH 3.7 to 8.2, a spread of 4.5 units across 230 soil components. 80% of the land falls in one class, so the county figure is a fair first guess for most yards here.

Clay, organic matter and rates

Topsoil here averages 3.3% clay and 1.46% organic matter, which this site treats as sandy. Moving it one pH unit takes about 3 lb of lime or 1.2 lb of sulfur per 100 sq ft. 0% of mapped components carry free carbonate (lime already in the ground).

Kodiak Island Borough against the rest of Alaska

pH 4.96 is 0.3 below the Alaska median of 5.26. 7 of 27 Alaska counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Kenai Peninsula Borough (4.85), Anchorage Borough (4.89), Dillingham Census Area (4.94), Wrangell-Petersburg Census Area (4.94), Kusilvak Census Area (old Wade Hampton) (5.04), Haines Borough (5.1), Valdez-Cordova Census Area (5.15), Matanuska-Susitna Borough (5.2).

The range in Alaska runs from Ketchikan Gateway Borough at 4.52 to Yakutat City and Borough at 6.08; Kodiak Island Borough sits 28% of the way up.